1. Field of the Invention
This invention relates to the separation of solids from liquids and more particularly it relates to orbital screen separators for removing cuttings and other solids from drilling muds.
2. Description of Prior Art
Various types of screen separators employ a woven or perforated screen in a positive orbital motion for the separation of solids from a liquid with good results. As the screen moves, separated solids are moved to its leading edge for ready discharge. In order to prevent stagnant areas of solids on the screen, it is bowed downwardly in its central portions relative to the edges secured to the oscillating mechanism. Generally, rails are mounted above the screen and extend along the axis of solid movements across the screen. The screen is tensioned at its edges so that it is firmly pressed in a bow-like curve against a resilient cushion carried on the lower portion of each rail. The cushion provides for a resilient buffer between the rail and the screen. Also, the screen is restricted in moving relative to the rail by the cushion. As a result, abrasive solids hopefully will not move between the cushion and the screen. If the screen moves relative to the cushion, entrapped solids cause severe and undesired wearing of the screen. Although the screen is under a tension of several hundred pounds of pull between its edges, a slight movement of the screen relative to the cushion does occur. Thus, entry of solids between the prior art cushion and the screen are a primary function of screen tension.
It has been found that the screen cushion must be uniquely designed so that it will function with the screen movements to keep solids from working their way between the cushion and the screen, within the parameters of screen tension and bowing permitted in conventionally operating screen separators. It is the purpose of this invention to provide such a unique screen cushion that can be employed with conventional screen separators so as to avoid the problems associated with resilient screen cushions that have been employed in conventional screen separators up to the present time.